package org.apache.commons.jcs.yajcache.lang.ref;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import org.apache.commons.jcs.yajcache.lang.annotation.*;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;

/**
 * {@link SoftReference} with an embedded key.
 *
 * @author Hanson Char
 */
@CopyRightApache
public class KeyedSoftReference<K,T> extends SoftReference<T>
        implements IKey<K>
{
    /** The embedded key. */
    private final @NonNullable @Immutable K key;

    /**
     * Creates a new soft reference with an embedded key that refers to
     * the given object.  The new
     * reference is not registered with any queue.
     *
     * @param key the embedded key of the new soft reference
     * @param referent object the new soft reference will refer to
     */
    public KeyedSoftReference(@NonNullable @Immutable K key, T referent)
    {
	super(referent);
        this.key = key;
    }
    /**
     * Creates a new soft reference with an embedded key that refers to
     * the given object and is registered with the given queue.
     *
     * @param key the embedded key of the new soft reference
     * @param referent object the new soft reference will refer to
     * @param q the queue with which the reference is to be registered,
     *          or <tt>null</tt> if registration is not required
     */
    public KeyedSoftReference(@NonNullable @Immutable K key, T referent,
            ReferenceQueue<? super T> q)
    {
        super(referent, q);
        this.key = key;
    }
    @Implements(IKey.class)
    public @NonNullable @Immutable K getKey() {
        return this.key;
    }
}
